In a sequence of manufacturing a semiconductor device, a film forming process of forming a nitride film such as a silicon nitride film (SiN film) or the like as an insulating film on a semiconductor wafer represented by a silicon wafer is performed. In this film forming process of the SiN film, a chemical vapor deposition (CVD) method is used.
When an SiN film (CVD-SiN) is embedded in a trench by the CVD method, voids or seams may be generated. In this case, a method of forming an SiN film by the CVD method is performed again after performing an etch back to a place where the voids or seams are generated is employed.
Recently, however, as devices have been reduced in size, step coverage is not sufficient for CVD-SiN, making it difficult to suppress generation of voids or seams even by the aforementioned method.
An atomic layer deposition (ALD) method has been known as a technique that allows film formation with step coverage better than that of the CVD method, and the ALD method is also used to embed an SiN film in a fine trench.
However, due to further reduction of devices in size, it is difficult to embed an SiN film, while preventing generation of voids or seams, even by the ALD method.